The present invention relates to the construction of a door which can be easily opened even if the door frame is deformed by the relative story displacement of the wall of the building at the time of an earthquake.
It is required that entrance doors of high-storied apartments, as well as the room doors and emergency exit doors of schools, hotels, hospitals and other buildings be designed to serve the purpose of protection against fires, noises, crimes, etc. However, earthquakes have been left out of consideration in the design of doors.
According to recent reports of investigation of damages by earthquakes, if walls are subjected to relative story displacement by a strong earthquake, door frames are deformed and it becomes impossible to open the doors. Therefore, it is sometimes impossible to escape from rooms; this is of special concern should a fire break out therein.
Thus, it is necessary to provide a door which can be opened easily even if the door frame is deformed.
In an attempt to meet the need, Japanese Utility Model Application No. Sho. 53-131843 provides a door in which the edge faces thereof and the inner faces of a door frame facing each other are inclined so that the outside panel of the door is larger in area than the inside panel thereof, thereby said door being pushed out of said door frame when said door frame is deformed.
In practice, however, the aforesaid door may not be pushed out of the door frame when the door and the door frame are brought into contact with each other, because large displacements of the door frame and the door, such as may be caused by an earthquake, are not considered in the design thereof with respect to the clearances between the door frame and the door.
In conventional doors, the clearances between the door frame and the door are only 3 to 4 mm and cannot absorb large deformations thereof caused by an earthquake.
With the deformation of the door frame, a dead bolt and a latch bolt of a door lock are vertically displaced within a bolt recess in the door frame. In conventional doors, the upper and lower clearances between the bolts and the bolt recess are so small that in such a case one of the bolts contacts an inner surface of the bolt recess and cannot be withdrawn therefrom.